Multimedia such as video and audio can be transmitted over a number of paths, including cable, the Internet, and broadcast. For instance, satellite or terrestrial broadcast stations can be used to transmit multimedia to mobile computing devices such as mobile telephones.
Typically, multimedia data is voluminous, which means that significant transmission path bandwidth, unfortunately a finite resource, must be used. This is particularly the case for high fidelity multimedia, e.g., high resolution video. That is, the higher the quality of service being provided, the more bandwidth must be used.
As recognized by the present invention, several multimedia streams can be pooled together in a single channel. The channel might have a constant overall bandwidth in terms of bit rate, i.e., the number of bits that can be transmitted in the channel per unit time cannot exceed the “bandwidth” of the channel. Typically, each stream in the channel will be accorded a fixed fraction of the bandwidth. Accordingly, the bit rate for each multimedia stream typically is fixed.
As further recognized by the present invention, however, a multimedia stream might require a higher bit rate for a given quality of service (QOS) some of the time and a lower bit rate for the same QOS at other times. As an example, in a video stream, when the video sequence makes a hard cut (i.e., a large amount of pixel changes are taking place), a higher bit rate is required to achieve the same QOS as could be achieved at other times with a lower bit rate when relatively little action is taking place. Or, in terms of audio streams, a higher bit rate might be required at the beginning of a speech or music segment than at other times during the stream to achieve the same QOS.
Having made the above critical recognitions, the present invention further understands that one multimedia stream in a channel might require a relatively low bit rate at the same time that another stream in the channel might require a relatively high bit rate, and that it consequently would be desirable to allocate the limited overall bandwidth of the channel in a way that can account for this.